#include<stdio.h>
int main()
{
    int a,i,b,n;
    printf("There are following friendly-numbers pair samller than 3000:\n");
    for(a=1; a<3000; a++)
    {
        for(b=0, i=1; i<=a/2; i++)
            if(!(a%i))b+=i;
        for(n=0, i=1; i<=b/2; i++)
            if(!(b%i))n+=i;
            if(n==a && a<b)
        printf("%4d..%4d,a,b");    

    }
}


//吴昌源
